Characteristics of Condensation Droplet Growth on Microholed Gradient Surfaces

It is a very important method to enhance heat transfer for dropwise condensation using hydrophobic surfaces. Microholed gradient surfaces are prepared with the polydimethyl-siloxane (PDMS) substrate using photolithography techniques. The dynamic processes of condensation droplet growth on gradient surfaces are observed. It is found that the fill rates of condensation droplets are different with the gradient variation of microholed surfaces, leading to the regular changes of droplet morphologies. According to the analysis of the surface coverage of condensation droplets, the energy barrier and radius of nucleation are further discussed. In addition, during the early stage of condensation, the maximum surface coverage is found when the area fraction is 0.5 by the speed analysis of droplets merging, due to the common influence of gradient surface tension and surface structure. © 2019, Science Press. All right reserved.